Deletes the org.teiid.8.2.x submodule

* To fully remove all references to this submodule, local repositories
  should do the following:
 * Remove the submodule reference in the main repository's .git/config file
 * Remove the actual directory 'plugins/teiid/org.teiid.8.2.x'

* This should result in the repository being clean and 8.2.x free
TEIIDDES-505 Closing VDB editor if user chooses to extract VDB files and synchronize VDB
TEIIDDES-1612: Fixes accumulation of inputs in transformation

* AttributeMappingHelper
 * The element collector visitor implementations store the returned
   elements in a field. As a consequence, using the visitor in a loop means
   the previously found elements are also returned with newly found
   elements.
 * Creates a new instance of the visitor each time it is required to
   avoiding erroneous caching of elements.
Improves performance of submodule project auto-builders
TEIIDDES-1614: Addresses validation error produced by new webservices

* TransformationValidator
 * The if-statement was modified during the 8.2 migration and lost 2 of its
   clauses, resulting in the certainty of firing. The consequence is the
   setting of the projectSymbols collection to empty when it is crucial for
   it to stay null.
 * The if-statement is only necessary for the 7.7.x resolver hence has been
   pushed down into its implementation using the postResolveCommand spi
   method